code: def unary_func_fixture():
      """
      Register a unary scalar function.
      """
      from pyarrow import compute as pc
  
      def unary_function(ctx, x):
          return pc.call_function(
              "add", [x, 1], memory_pool=ctx.memory_pool
          )
  
      func_name = "y=x+1"
      unary_doc = {
          "summary": "add function",
          "description": "test add function",
      }
      pc.register_scalar_function(
          unary_function,
          func_name,
          unary_doc,
          {"array": pa.int64()},
          pa.int64(),
      )
      return unary_function, func_name
  
file_path: arrow/python/pyarrow/conftest.py
imports: import pytest
  import pyarrow
  from pyarrow import Codec
  from pyarrow import fs
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: unary_func_fixture() and returns: unary_function,  func_name, pc